Many food and pharmaceutical products must be packaged in moisture-impervious containers. Historically, glass and metal containers were used for this purpose. More recently, to reduce cost and make the containers disposable, plastics have been combined in multilayer composite structures, with one layer providing the desired barrier to moisture and another layer the required structural properties. An intervening adhesive layer has generally been needed to adhere the other two together. The containers are manufactured by first forming a composite sheet, either by coextrusion or by laminating together separately-formed sheets, and then thermally forming the containers from the sheet.